Tertiary lock

ABSTRACT

The subject matter of this specification can be embodied in, among other things, a thrust reverser tertiary lock apparatus that includes a probe affixed to an aircraft engine frame and having a shaft having a barb at a first end and configurable to a first configuration and a second configuration, and a receiver affixed to a thrust reverser transcowl slider configured to accommodate the barb and having an end wall with an aperture defined therein, the aperture shaped to permit escapement of the barb in the first configuration and prevent escapement of the barb in the second configuration.

TECHNICAL FIELD

This instant specification relates to an aircraft thrust reverseractuation locking system.

BACKGROUND

Contemporary aircraft engines may include a thrust reverse actuationsystem to assist in reducing the aircraft speed during landing. Typicalthrust reversers include a movable transcowl that, when in the activeposition, reverses at least a portion of the airflow passing through theengine.

Accidental or inadvertent activation and deployment of thrust reversersat inappropriate times can be dangerous or deadly. Accidental deploymenton the ground while ground crews are performing service on the enginecan result in injury or death. Accidental activation during flight cancause a catastrophic loss of airspeed or failure of the airframe.Mechanical malfunctions, such as a loss of hydraulic pressure, can alsoallow a reverser to move out of the stowed position at an inappropriatetime.

To prevent accidental or unintentional thrust reverser deployment,locking mechanisms are used. Before the thrust reverser can be movedfrom its stowed position, the lock must first be disengaged. Somecurrent reverser lock designs implement rotating jaws to engage a probe.Such designs can be heavy and mechanically complex, which adds weightand maintenance requirements to the aircraft on which they areinstalled.

SUMMARY

In general, this document describes an aircraft thrust reverseractuation locking system.

In a first aspect, a thrust reverser tertiary lock apparatus includes aprobe affixed to an aircraft engine frame and having a shaft having abarb at a first end and configurable to a first configuration and asecond configuration, and a receiver affixed to a thrust reversertranscowl slider configured to accommodate the barb and having an endwall with an aperture defined therein, the aperture shaped to permitescapement of the barb in the first configuration and prevent escapementof the barb in the second configuration.

Various embodiments can include some, all, or none of the followingfeatures. The thrust reverser tertiary lock apparatus can include arotary actuator configured to rotate the barb about an axis, wherein thebarb is rotatable by the rotary actuator between the first configurationand the second configuration. The aperture can be rotationallyasymmetric relative to the axis and the barb is rotationally asymmetricabout the axis between the first configuration and the secondconfiguration, such that the barb is escapable from the receiver throughthe aperture in the first configuration and the barb is interfered withby the end wall such that escapement of the barb is prevented in thesecond configuration. The barb can include at least one arm having afirst end connected to the shaft and a second end that is biased awayfrom the shaft, wherein the arm defines the rotational asymmetry of thebarb. The first end can be pivotably connected to the shaft andconfigured to contact an edge of the aperture and pivot axially to passthrough the aperture during penetration of the end wall by the barb inthe second configuration, and configured to pivot away from the shaftand interfere with escapement of the barb in the second configuration.The barb can be configured to rotate to the first configuration whenactivated and rotate to the second configuration when deactivated. Thebarb can be a bevel configured to contact an edge of the aperture andurge rotation of the barb about the axis from the second configurationto the first configuration during penetration of the aperture by thebarb. An edge of the aperture can include a bevel configured to contactthe barb and urge rotation of the barb about the axis from the secondconfiguration to the first configuration during penetration of theaperture by the barb. The thrust reverser tertiary lock apparatus canalso include a torsion bias spring configured to rotate the barb aboutthe axis from the first configuration to the second configuration afterthe barb has completed penetration of the bevel. The barb can have afirst size in the first configuration and can have a second size in thesecond configuration, wherein the first size is smaller than theaperture such that the barb is able to penetrate and escape the aperturein the first configuration, and the second size is larger than theaperture such that the barb is retained by the receiver and escapementof the barb through the aperture is prevented by interference betweenthe barb and the end wall in the second configuration. The barb can bespring biased towards the second size. The probe can include a linearactuator, and the barb has at least one arm linked to the linearactuator, wherein the linear actuator is configured to extend the armfrom the first configuration in which the arm extends from the shaft afirst distance to define the first size, to the second configuration inwhich the arm extends from the shaft a second distance greater than thefirst distance to define the second size.

In a second aspect, a method of operating a thrust reverser tertiarylock includes locking a thrust reverser tertiary lock by penetrating, bya barb at a first end of a shaft of a probe, an aperture defined in anend wall of a receiver shaped to accommodate the barb, configuring thebarb to a first configuration, and preventing, by the end wall,escapement of the barb though the aperture in the first configuration,and unlocking the thrust reverser tertiary lock by configuring the barbto a second configuration, and permitting escapement of the barb throughthe aperture in the second configuration.

Various implementations can include some, all, or none of the followingfeatures. Locking the thrust reverser tertiary lock can also includeconfiguring, while in an escaped configuration, the barb to the firstconfiguration, contacting the barb to an edge of the aperture, whereincontact between the barb and the edge urges the barb from the firstconfiguration to the second configuration, penetrating, by the probe,the aperture, and reconfiguring, after the barb has passed through theaperture, the barb to the first configuration. The barb can include abevel configured to contact the edge of the aperture and urge rotationof the barb about a primary axis of the shaft from the firstconfiguration to the second configuration during penetration of theaperture by the barb. The edge of the aperture can include a bevelconfigured to contact the barb and urge rotation of the barb about aprimary axis of the shaft from the first configuration to the secondconfiguration during penetration of the aperture by the barb.Reconfiguring, after the barb has passed through the aperture, the barbto the first configuration, can also include rotating, by a torsion biasspring, the barb about the axis from the first configuration to thesecond configuration after the barb has completed penetration of thebevel. The barb can include an arm having a first end that is pivotablyconnected to the shaft and configured to contact an edge of the apertureand pivot toward the shaft from the first configuration to the secondconfiguration to pass through the aperture during penetration of the endwall by the barb, and configured to pivot away from the shaft from thesecond configuration to the first configuration and interfere withescapement of the barb in the first configuration. Configuring the barbto the first configuration can include rotating, by a rotary actuator,the barb about an axis from a second rotary position to a first rotaryposition. Configuring the barb to the second configuration can includerotating, by a rotary actuator, the barb about an axis from a firstrotary position to a second rotary position. The barb can have a firstsize in the first configuration and has a second size in the secondconfiguration, wherein the second size is smaller than the aperture suchthat the barb is able to penetrate and escape the aperture in the secondconfiguration, and the first size is larger than the aperture such thatthe barb is retained by the receiver and escapement of the barb throughthe aperture is prevented by interference between the barb and the endwall in the first configuration, and wherein configuring the barb to thefirst configuration can include actuating, by a linear actuator, atleast one arm linked to the linear actuator, extending, based on theactuating, the arm from the second configuration in which the armextends from the shaft a first distance to define the first size, to thefirst configuration in which the arm extends from the shaft a seconddistance greater than the first distance to define the second size. Thebarb can have a first size in the first configuration and has a secondsize in the second configuration, wherein the second size is smallerthan the aperture such that the barb is able to penetrate and escape theaperture in the second configuration, and the first size is larger thanthe aperture such that the barb is retained by the receiver andescapement of the barb through the aperture is prevented by interferencebetween the barb and the end wall in the first configuration, andwherein configuring the barb to the first configuration can includeactuating, by a linear actuator, at least one arm linked to the linearactuator, and retracting, based on the actuating, the arm from the firstconfiguration in which the arm extends from the shaft a first distanceto define the first size, to the second configuration in which the armextends from the shaft a second distance less than the first distance todefine the second size. The barb can be spring-biased to the first size.

The systems and techniques described here may provide one or more of thefollowing advantages. First, the system replaces a conventionaltwo-piece, jaws-type lock mechanism with a much simpler rotary-typedesign. Second, the system uses a rotary mechanism that is smaller andless complex than the large and heavy moving jaws of jaws-type lockmechanism designs. Third, the system uses a one moving piece mechanisminstead of the complex slot and bearing mechanism that is used to swingthe jaws of a jaws-type lock. Fourth, the system is lighter and morereliable than jaws-type lock mechanism.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of an example turbofan jet engine with aportion of the outer nacelle cut away for clarity.

FIG. 2 is a schematic view of the engine of FIG. 1 with an exemplarythrust reverser.

FIG. 3 is a schematic view of the engine of FIG. 1 with an alternativeexemplary thrust reverser.

FIG. 4A is a sectional side view of an exemplary thrust reversertertiary lock in a locked configuration.

FIG. 4B is a sectional side view of an exemplary thrust reversertertiary lock in an unlocked configuration.

FIG. 5 is a front view of an exemplary receiver of a thrust reversertertiary lock.

FIGS. 6A and 6B are side views of an exemplary probe of a thrustreverser tertiary lock in a locked and unlocked configuration.

FIGS. 6C and 6D are end views of an exemplary probe of a thrust reversertertiary lock in a locked and unlocked configuration.

FIG. 7 is a side view of an exemplary thrust reverser tertiary lock in alocked configuration while escaped.

FIG. 8 is a front view of an exemplary receiver with bevels.

FIGS. 9A and 9B are side views of an exemplary barb with bevels.

FIG. 10A is a sectional side view of another exemplary thrust reversertertiary lock in a locked configuration.

FIG. 10B is a sectional side view of another exemplary thrust reversertertiary lock in an unlocked configuration.

FIGS. 11A and 11B are side views of another exemplary barb.

FIG. 12 is a sectional side view of another exemplary thrust reversertertiary lock.

FIG. 13 is a zoomed sectional side view of another exemplary thrustreverser tertiary lock.

FIG. 14A is a zoomed side view of another probe in a lockedconfiguration.

FIG. 14B is a zoomed side view of another exemplary probe an unlockedconfiguration.

FIG. 15 is a flow diagram of an example process of locking and unlockinga thrust reverser tertiary lock.

DETAILED DESCRIPTION

This document describes systems and techniques for reversing aircraftturbine engine airflow. A thrust reverser with at least one movableelement, which is movable to and from a reversing position, may be usedto change the direction of the bypass airflow. In the reversingposition, the movable element may be configured to reverse at least aportion of the bypass airflow.

Locking mechanisms engage the thrust reversers to prevent accidentalactivation or accidental deployment (e.g., during flight, during groundmaintenance operations). The paragraphs below describe a mechanism thatprovides such locking in an assembly that is relatively lighter and lesscomplex than existing designs.

FIG. 1 illustrates an example turbofan jet engine assembly 10 having aturbine engine 12, a fan assembly 13, and a nacelle 14. Portions of thenacelle 14 have been cut away for clarity. The nacelle 14 surrounds theturbine engine 12 and defines an annular airflow path or annular bypassduct 16 through the jet engine assembly 10 to define a generallyforward-to-aft bypass airflow path as schematically illustrated by thearrow 18. A combustion airflow is schematically illustrated by thearrows 19.

A thrust reverser with at least one movable element, which is movable toand from a reversing position, may be used to change the direction ofthe bypass airflow. In the reversing position, the movable element maybe configured to reverse at least a portion of the bypass airflow. Thereare several methods of obtaining reverse thrust on turbofan jet engineassemblies. FIG. 2 schematically illustrates one example of a thrustreverser 20 that may be used in the turbofan jet engine assembly 10. Thethrust reverser 20 includes a movable element 22. The movable element 22has been illustrated as a cowl portion that is capable of axial motionwith respect to the forward portion of the nacelle 14. A hydraulicactuator 24 may be coupled to the movable element 22 to move the movableelement 22 into and out of the reversing position. In the reversingposition, as illustrated, the movable element 22 limits the annularbypass area between the movable element 22 and the turbine engine 12, italso opens up a portion 26 between the movable element 22 and theforward portion of the nacelle 14 such that the air flow path may bereversed as illustrated by the arrows 28. An optional deflector or flap(also known as a blocker door) 29 may be included to aid in directingthe airflow path between the movable element 22 and the forward portionof the nacelle 14.

FIG. 3 schematically illustrates an alternative example of a thrustreverser 30. The thrust reverser 30 includes a movable element 32. Themovable element 32 has been illustrated as a deflector, which may bebuilt into a portion of the nacelle 14. A hydraulic actuator 34 may becoupled to the movable element 32 to move the movable element 32 intoand out of the reversing position. In the reversing position, shown inphantom and indicated at 36, the movable element 32 turns that airoutward and forward to reverse its direction as illustrated by thearrows 38. An optional deflector, blocker door, or flap 39 may beincluded to aid in directing the airflow path outward.

In both illustrative examples, the thrust reverser changes the directionof the thrust force. Both the thrust reverser 20 and the thrust reverser30 have been described as hydraulically operated systems and a hydraulicactuator has been schematically illustrated. In some embodiments, thethrust reverser 20 and/or the thrust reverser 30 can be powered by otherfluids (e.g., pneumatic), by electro-mechanical actuators, or by anyother appropriate power source or actuator type.

FIG. 4A is a sectional side view of an exemplary thrust reversertertiary lock system 400 in a locked configuration. FIG. 4B is asectional side view of the exemplary thrust reverser tertiary locksystem 400 in an unlocked configuration. In some implementations, thethrust reverser tertiary lock system 400 is an apparatus that can beused to lock the example thrust reverser 20 or the example thrustreverser 30 of FIGS. 2 and 3.

The exemplary system 400 includes a probe assembly 410 and a receiverassembly 450. The probe assembly 410 is configured to be affixed to astructure 401, such as an airframe member or an aircraft engine frame.The receiver assembly 450 is configured to be affixed to a structure402, such as a thrust reverser transcowl slider. In some embodiments,the probe assembly 410 can be affixed to the structure 402 and thereceiver assembly 450 can be affixed to the structure 401.

The receiver assembly 450 includes a base 460 and an affixment point 470affixed to the base 460. The affixment points 470 provide bores throughwhich two fasteners 472 (e.g., bolts, screws) are passed to removablyaffix the base to the structure 402.

A housing 480 is also affixed to the base 460. The housing 480 includesan aperture 482 formed in an end wall 484. A cavity 486 is definedwithin the housing 480, and is partly defined by the end wall 484.

Referring now to FIG. 5, a front view of the exemplary receiver assembly450 is shown. The aperture 482 is a rotationally asymmetrical opening inthe end wall 484. For example, if the aperture 482 were to be rotated inthe plane of FIG. 5, the shape of the aperture 482 would be differentrelative to the shape of the aperture 482 in its original position. Inthe illustrated example, the aperture 482 is rectangular (e.g., with alength that is greater than its width). In some embodiments, theaperture 482 can have other rotationally asymmetrical shapes that can beactivated and partly rotated into a position that is asymmetricalrelative to its original position (e.g., triangular, oval, trapezoidal,semi-cylindrical, polygonal).

Referring again to FIGS. 4A and 4B, the probe assembly 410 includes ashaft 420 defining a longitudinal axis 422. The shaft 420 isrotationally coupled at one end to a rotary actuator 430. The rotaryactuator 430 is configured to activate and at least partly rotate theshaft 420 about the longitudinal axis between an unlocked configuration(e.g., a first rotational position) and a locked configuration (e.g., asecond rotational position that is different from the first).

The shaft 420 includes a barb 440 at its other end, opposite the rotaryactuator 430. Referring now to FIGS. 6A-6D, FIG. 6A is a magnified sideview of the probe 410 the thrust reverser tertiary lock system 400 in anunlocked configuration, and FIG. 6B is a magnified side view of theprobe 410 of the thrust reverser tertiary lock system 400 in a lockedconfiguration. FIG. 6C is a magnified end view of the probe 410 thethrust reverser tertiary lock system 400 in an unlocked configuration,and FIG. 6D is a magnified end view of the probe 410 of the thrustreverser tertiary lock system 400 in a locked configuration.

The barb 440 is rotationally asymmetrical about the longitudinal axis422. For example, when the shaft 420 is rotated, the orientation of thebarb 440 can be changed to a position in that is not symmetrical aboutthe longitudinal axis 422 relative to its original position. In theillustrated example, the barb 440 is rectangular (e.g., with a lengththat is greater than its width) when viewed end-on, such as shown inFIGS. 6C and 6D. In some embodiments, barb 440 can have otherrotationally asymmetrical shapes that can be partly rotated into aposition that is asymmetrical relative to its original position (e.g.,triangular, oval, trapezoidal, semi-cylindrical, polygonal).

Referring again to FIG. 4A, when rotated into the locked configuration,the barb 440 mechanically interferes with the end wall 484 of thereceiver assembly 450 and the receiver assembly 450 prevents escapementof the probe 410. For example, when the rectangular shape of the barb440 is rotated relative to the shape of the aperture 482 (e.g., 90degrees in the illustrated example), the barb 440 is retained with inthe cavity 486. In such a locked, retained configuration, as shown inthe illustrated example of FIG. 4A, the structure 402 is mechanicallyretained to the structure 401 through the system 400. In use, such alocked and retained configuration can be used to lock a moveable portionof a thrust reverser to an engine frame or airframe to preventinadvertent or accidental deployment of the thrust reverser.

Referring again to FIG. 4B, when rotated into the unlockedconfiguration, the barb 440 can fit through the aperture 482, whichpermits escapement of the barb 440 from the cavity 486 through the endwall 484. In such an unlocked configuration, as shown in the illustratedexample of FIG. 4B, the structure 402 is mechanically released from thestructure 401. In use, such an unlocked configuration can permitmovement of a moveable portion of a thrust reverser relative to anengine frame or airframe, for example, to permit deployment of thethrust reverser.

In some embodiments, the probe 410 may be configured to remain in thelocked configuration by default. For example, regulatory agencies (e.g.,the FAA) may require the system 400 to fail “safe” and keep the receiverassembly 450 locked to and engaged with the probe 410 if power to therotary actuator 430 is lost. In some embodiments, the shaft 420 may bebiased to the locked configuration by a torsion or linear spring. Forexample, the rotary actuator 430 may include a spring that is configuredto urge the probe into the locked configuration. When the rotaryactuator 430 is energized, the rotary actuator 430 overcomes the springbias to unlock the probe 410. When the rotary actuator 430 isde-energized, the spring can urge the probe 410 back to the lockedconfiguration.

FIG. 7 is a side view of an exemplary thrust reverser tertiary locksystem 700 in a locked configuration while escaped. The system 700 issubstantially similar to the exemplary thrust reverser tertiary locksystem 400 of FIGS. 4A and 4B, except one or both of a barb 740 of aprobe 710, and an end wall 784 of a receiver 750, are modified relativeto the example barb 440 and the example end wall 484. The end wall 784will be discussed further in the description of FIG. 8, and the barb 740will be discussed further in the description of FIGS. 9A and 9B.

In the example system 400, the end wall 484 not only prevents escapementof the probe 410 from engagement with the receiver assembly 450 whenlocked, without modification the end wall 484 can also preventengagement of the probe 410 with the receiver assembly 450 (e.g.,penetration of the end wall 484 by the barb 440) when the probe 410 islocked and disengaged from the receiver assembly 450. However, in someimplementations (e.g., under some regulatory environments), the system700 may be configured to fail “safe” by permitting the structure 402(e.g., a thrust reverser slider) to reengage and relock with thestructure 401 (e.g., engine frame) even when the rotary actuator 430 hasnot been energized (e.g., by accident or by malfunction).

The exemplary system 700 includes modifications that can permitengagement of the probe 710 to the receiver 750 when locked anddisengaged. For example, the system 700 can secure the structure 402 tothe structure 401 even when the rotary actuator 430 has not be energizedprior to retraction of the structure 402 (e.g., somebody forgot tounlock the probe 710 prior to retraction, the rotary actuatormalfunctions and fails to move the probe 710 to the unlockedconfiguration during retraction).

Similar to the barb 440, the barb 740 is rotationally asymmetrical andcan be rotated between a locked configuration and an unlockedconfiguration, and similar to the end wall 484, the end wall includes arotationally asymmetrical aperture 782 that is configured to preventescapement of the barb 740 from the receiver 750 in the lockedconfiguration. However, without additional features such as those thatwill be discussed below, such a configuration can also preventpenetration of the end wall 784 by the barb 740 while the barb 740 isescaped and locked. The barb 740 and the end wall 784 include featuresthat assist in urging the probe 710 from a locked configuration to anunlocked configuration when the receiver 750 is moved from an extendedposition toward a retracted position.

Referring now to FIG. 8, a front view of an exemplary receiver 750 isshown. The receiver 750 is substantially similar to the example receiverassembly 450, except that the end wall 784 includes a collection ofbevels 786. The bevels 786 are configured as a helical or spiral slopethat starts at the front face of the end wall 784, and slopes downwardand rotationally though a portion of the thickness of the front face 784to the aperture 482. When the receiver 750 is moved linearly toward theprobe 710, the barb 740 contacts a portion of the bevels 786. The bevels786 are configured to convert the linear motion between the receiver 750and the probe 710 into rotary motion of the probe 710 (e.g., by urgingrotation as the barb 740 slides down the slope of the bevels 786). Insome embodiments, the force of the rotary motion provided by theinteraction of the barb 740 and the bevels 786 can be sufficient toovercome a spring bias that is configured to otherwise urge the barb 740toward the locked configuration.

Eventually, the barb 740 is rotated into the unlocked configurationrelative to the receiver 750. In the unlocked configuration, the barb740 can continue to penetrate the remainder of the thickness of the endwall 784 through the aperture 482. Once the barb has fully penetratedthe end face 784, the barb 740 can be rotated back to the lockedconfiguration, for example by energizing the rotary actuator 430 or by aspring bias configured to urge the barb 740 toward the lockedconfiguration (e.g., to reversibly couple the structure 402 to thestructure 401).

FIGS. 9A and 9B are opposing side views of an exemplary barb 940 withbevels. In some embodiments, the barb 940 can be the example barb 440 ofFIGS. 4A and 4B, or the example barb 740 of FIG. 7.

The barb 940 is substantially similar to the example barb 440, exceptthat the barb 940 includes a collection of bevels 950. The bevels 950are configured as an angular, helical, or spiral slope that starts at amajor face 952 of opposite sides of the barb 940, and slopes downwardand rotationally though a portion of the thickness of the barb 940. Insome embodiments, the bevels 950 can be complementary to the bevels 786of the example receiver 750. In embodiments in which the barb 940 isused with the example system 700, when the receiver 750 is movedlinearly toward the probe 710, the barb 740 contacts a portion of thebevels 950. The bevels 950 are configured to convert the linear motionbetween the receiver 750 and the probe 710 into rotary motion of theprobe 710 (e.g., by urging rotation as the barb 740 slides down theslope of the bevels 950). In some embodiments, the force of the rotarymotion provided by the interaction of the barb 740 and the bevels 950can be sufficient to overcome a spring bias that is configured tootherwise urge the barb 740 toward the locked configuration.

FIG. 10A is a sectional side view of another exemplary thrust reversertertiary lock system 1000 in a locked configuration. FIG. 10B is asectional side view of the system 1000 in an unlocked configuration. Ingeneral, the system 1000 is substantially similar to the example system400 of FIGS. 4A and 4B, but with a different barb configuration andreceiver configuration. The system 1000 includes the structure 401 andthe structure 402, which are releasably linked by a probe 1010 and areceiver 1050.

The probe 1010 includes the rotary actuator 430 and the shaft 420. Theprobe 1010 also includes a barb 1040. FIGS. 11A and 11B are magnifiedside views of the exemplary barb 1040 of FIGS. 10A and 10B in a lockedconfiguration (e.g., FIG. 11A) and an unlocked configuration (e.g., FIG.11B).

The barb 1040 includes a base 1042 that is affixed to the shaft 420.Extending angularly away from the base 1042 is an arm 1044 a and an arm1044 b. The arms 1044 a, 1044 b are configured to pivot on pivot points1046. A bias member (e.g., spring) (not shown) is configured to bias thearms 1044 a, 1044 b away from the shaft 420. When a force, greater thanthe bias force, is applied to the arms 1044 a, 1044 b, the arms 1044 a,1044 b pivot toward a retracted position that is relatively moreparallel with the shaft 420 than when in their extended, biasedposition.

The barb 1040 is rotationally asymmetrical about the longitudinal axis422. For example, when the shaft 420 is rotated, the orientation of thebarb 1040 can be changed to a position in that is not symmetrical aboutthe longitudinal axis 422 relative to its original position. In theillustrated example, the arms 1044 a, 1044 b extend from opposite sidesof the based 1042 a distance that is greater than the thickness of thebase 1042 and shaft 420.

Referring again to FIGS. 10A and 11A, when rotated into the lockedconfiguration, the barb 1040 mechanically interferes with the end wall484 of the receiver 1050 and the receiver 1050 prevents escapement ofthe probe 1010. For example, when the arms 1044 a, 1044 b of the barb1040 are rotated relative to the shape of the aperture 482 (e.g., 90degrees in the illustrated example), the barb 1040 is retained with inthe cavity 486. In such a locked, retained configuration, as shown inthe illustrated example of FIG. 10A, the structure 402 is mechanicallyretained to the structure 401 through the system 1000. In use, such alocked and retained configuration can be used to lock a moveable portionof a thrust reverser to an engine frame or airframe to preventinadvertent or accidental deployment of the thrust reverser.

Referring again to FIGS. 10B and 11B, when rotated into the unlockedconfiguration, the barb 1040 can fit through the aperture 482, whichpermits escapement of the barb 1040 from the cavity 486 through the endwall 484. In such an unlocked configuration, as shown in the illustratedexample of FIG. 10B, the structure 402 is mechanically released from thestructure 401. In use, such an unlocked configuration can permitmovement of a moveable portion of a thrust reverser relative to anengine frame or airframe, for example, to permit deployment of thethrust reverser.

In some embodiments, the probe 1010 may be configured to remain in thelocked configuration by default. For example, the shaft 420 may bebiased to the locked configuration by a spring. When the rotary actuator430 is energized, the rotary actuator 430 overcomes the spring bias tounlock the probe 1010. When the rotary actuator 430 is de-energized, thespring can urge the probe 1010 back to the locked configuration.

FIG. 12 is a side view of the exemplary thrust reverser tertiary locksystem 1000 in a locked configuration while escaped. In the examplesystem 1000, the end wall 484 prevents escapement of the probe 410 fromengagement the receiver assembly 450 when locked. However, in someimplementations (e.g., under some regulatory environments), the system1000 may be configured to fail “safe” by permitting the structure 402(e.g., a thrust reverser slider) to reengage and relock with thestructure 401 (e.g., engine frame) even when the rotary actuator 430 hasnot been energized (e.g., by accident or by malfunction).

FIG. 13 is a zoomed sectional side view of the exemplary thrust reversertertiary lock system 1000 of FIGS. 10A and 10B. The system 1000 includesmodifications that can permit engagement of the probe 1010 to thereceiver 1050 when locked and disengaged. For example, the system 1000can secure the structure 402 to the structure 401 even when the rotaryactuator 430 has not been energized prior to retraction of the structure402 (e.g., somebody forgot to unlock the probe 1010 prior to retraction,the rotary actuator malfunctions and fails to move the probe 1010 to theunlocked configuration during retraction).

As discussed above, the barb 1040 is rotationally asymmetrical and canbe rotated between a locked configuration and an unlocked configuration,and the end wall 484 includes the rotationally asymmetrical aperture 482that is configured to prevent escapement of the barb 1040 from thereceiver 1050 in the locked configuration. The arms 1044 a, 1044 b areconfigured to permit penetration of the end wall 484 by the barb 1040while the barb 1040 is escaped and locked.

By default, the arms 1044 a, 1044 b are biased away from the shaft 420toward an extended configuration that extends to a size that isrelatively larger than the size of the aperture 482. When the arms 1044a, 1044 b are folded back toward the shaft, the arms 1044 a, 1044 b havea retracted size that is relatively smaller than the size of theaperture 482.

As the receiver 1050 is moved linearly toward the probe 1010, the barb1040 contacts a portion of the end wall 484. The arms 1044 a, 1044 b areconfigured to pivot or otherwise fold inward toward the shaft 420 as thebarb 1040 penetrates through the aperture 482. The force of the linearmotion is sufficient to overcome the spring bias that is configured toextend the arms 1044 a, 1044 b toward their extended configuration. Withthe arms 1044 a, 1044 b in the smaller, retracted position, the barb1040 can fit through the aperture 482 even when the probe 1010 is in thelocked configuration. Once the barb 1040 completely penetrates the endwall 484, the spring bias causes the arms 1044 a, 1044 b to snap back totheir larger, extended positions, which locks the probe 1010 to thereceiver 1050.

FIGS. 14A and 14B show an example thrust reverser tertiary lock system1400. FIG. 14A is a zoomed side view of an example probe 1410 in alocked configuration. FIG. 14B is a zoomed side view of the probe 1410an unlocked configuration. In general, the probe 1410 is substantiallysimilar to the example probe 1010 of FIGS. 10A and 10B, but includes abarb 1440 that is actively extendible and retractable instead of, or inaddition to, being rotatable.

The probe 1410 includes a shaft 1420. The probe 1410 also includes abarb 1440. The barb 1440 includes a base 1442 that is affixed to theshaft 420. Extending angularly away from the base 1442 is an arm 1444 aand an arm 1444 b. The arms 1444 a, 1444 b are configured to pivotrelative to the base 1442. A pair of linkages 1446 are pivotablyconnected at their first ends to the arms 1444 a, 1444 b, and arepivotably connected at their second ends to an actuation rod 1422. Theactuation rod 1422 is coupled to a linear actuator (not shown)configured to urge linear movement of the actuation rod 1422. Linearmovement of the actuation rod 1422 (e.g., substantially parallel to theshaft 1420) extends and retracts the arms 1444 a, 1444 b, as will bediscussed further below.

Referring to FIG. 14A, when the actuation rod 1422 is urged toward thebarb 1440, as indicated by the arrow 1490, the linkages 1446 push intothe arms 1444 a and 1444 b, urging the arms 1444 a, 1444 b to pivot, asindicated by the arrows 1492, toward an extended position that isrelatively larger than the size of the aperture 482. In the extended,locked configuration, the end wall 484 mechanically interferes with thebarb 1440 and prevents disengagement of the probe 1410 from the receiverassembly 450.

Referring to FIG. 14B, when the actuation rod 1422 is urged away fromthe barb 1440, as indicated by the arrow 1494, the linkages 1446 pullupon the arms 1444 a and 1444 b, drawing the arms 1444 a, 1444 b topivot, as indicated by the arrows 1496, toward a retracted position thatis relatively smaller than the size of the aperture 482. In theretracted, unlocked configuration, the end wall 484 does notmechanically interferes with the barb 1440 to prevent disengagement ofthe probe 1410 from the receiver assembly 450.

FIG. 15 is a flow diagram of an example process 1500 of locking andunlocking a thrust reverser tertiary lock. In some implementations, theprocess 1500 can be used with the example thrust reverser tertiary locksystem 400 of FIGS. 4A-6D, the example thrust reverser tertiary locksystem 700 of FIGS. 7-9B, the example thrust reverser tertiary locksystem 1000 of FIGS. 10A-13, and/or the example thrust reverser tertiarylock system 1400 of FIGS. 14A and 14B.

At 1510, a thrust reverser tertiary lock is locked. For example, thethrust reverser tertiary lock system 400 can be locked. To lock thelock, several steps are performed.

At 1512, a barb at a first end of a shaft of a probe penetrates anaperture defined in an end wall of a receiver shaped to accommodate thebarb. For example, the receiver assembly 450, as depicted in FIG. 4B,can be moved linearly closer to the probe 410 until the barb 440penetrates the aperture 482.

At 1514, the barb is configured to a first configuration. For example,the probe 410 can be reconfigured to the locked configuration asdepicted in FIG. 4A.

At 1516 escapement of the barb, in the first configuration, though theaperture is prevented by the end wall. For example, if the receiverassembly 450 is moved away from the probe 410, the barb 440 will becaught by the end wall 484 and prevented from escaping. As such, thestructure 402 will be locked to the structure 401.

In some embodiments, locking the thrust reverser tertiary lock can alsoinclude configuring, while in an escaped configuration, the barb to thefirst configuration, contacting the barb to an edge of the aperture,wherein contact between the barb and the edge urges the barb from thefirst configuration to the second configuration, penetrating, by theprobe, the aperture, and reconfiguring, after the barb has passedthrough the aperture, the barb to the first configuration. In someembodiments, the barb includes a bevel configured to contact the edge ofthe aperture and urge rotation of the barb about a primary axis of theshaft from the first configuration to the second configuration duringpenetration of the aperture by the barb. For example, the barb 940includes the bevels 950 that can contact the edges of the aperture 482to urge rotation of the barb 940 to permit penetration of the end wall784 by the barb 940. In some embodiments, the edge of the aperture caninclude a bevel configured to contact the barb and urge rotation of thebarb about a primary axis of the shaft from the first configuration tothe second configuration during penetration of the aperture by the barb.For example, the end wall 784 includes the bevels 786 that can urgerotation of the barb 740 to permit penetration of the end wall 784 bythe barb 940.

In some embodiments, reconfiguring, after the barb has passed throughthe aperture, the barb to the first configuration, can include rotating,by a torsion bias spring, the barb about the axis from the firstconfiguration to the second configuration after the barb has completedpenetration of the bevel. For example, the barb 740 can be spring-biasedby a torsion spring (not shown) connected to the shaft. The rotaryactuator 430, the bevels 786, and/or the bevels 950 can torque the shaftagainst the force of the spring, and once the barb 740 has passedthrough the aperture 782, the force of the spring can snap the barb 740into the locked configuration.

In some embodiments, the barb can include an arm having a first end thatis pivotably connected to the shaft and configured to contact an edge ofthe aperture and pivot toward the shaft from the first configuration tothe second configuration to pass through the aperture during penetrationof the end wall by the barb, and configured to pivot away from the shaftfrom the second configuration to the first configuration and interferewith escapement of the barb in the first configuration. For example, thebarb 1040 includes the arms 1044 a, 1044 b that can fold back to permitpassage of the barb 1040 through the aperture 482, and expand to preventescapement of the barb 1040 through the end wall 484.

At 1520, the thrust reverser tertiary lock is unlocked. For example, thethrust reverser tertiary lock system 400 can be unlocked. To unlock thelock, several steps are performed.

At 1522, the barb is configured to a second configuration. For example,the barb 440 can be reconfigured to the unlocked configuration. In theunlocked configuration, the barb 440 can fit through the aperture 482.

At 1524 escapement of the barb through the aperture in the secondconfiguration is permitted. For example, when the barb 440 is in theunlocked configuration and the structure 402 is moved linearly away fromthe structure 401, the barb 440 can pass through the aperture 482,allowing the structure 402 to be unlocked from the structure 401.

In some embodiments, configuring the barb to the first configuration caninclude rotating, by a rotary actuator, the barb about an axis from asecond rotary position to a first rotary position. For example, therotary actuator 430 or a spring can rotate the barb 440 to the unlockedconfiguration shown in FIGS. 4B, 6B, and 6D.

In some embodiments, configuring the barb to the second configurationcan include rotating, by a rotary actuator, the barb about an axis froma first rotary position to a second rotary position. For example, therotary actuator 430 or a spring can urge rotation of the barb 440 to thelocked configuration shown in FIGS. 4A, 6A, and 6C.

In some embodiments, the barb can have a first size in the firstconfiguration and can have a second size in the second configuration,wherein the second size is smaller than the aperture such that the barbis able to penetrate and escape the aperture in the secondconfiguration, and the first size is larger than the aperture such thatthe barb is retained by the receiver and escapement of the barb throughthe aperture is prevented by interference between the barb and the endwall in the first configuration, wherein configuring the barb to thefirst configuration can include actuating, by a linear actuator, atleast one arm linked to the linear actuator, extending, based on theactuating, the arm from the second configuration in which the armextends from the shaft a first distance to define the first size, to thefirst configuration in which the arm extends from the shaft a seconddistance greater than the first distance to define the second size. Insome embodiments, the barb can have a first size in the firstconfiguration and has a second size in the second configuration, whereinthe second size is smaller than the aperture such that the barb is ableto penetrate and escape the aperture in the second configuration, andthe first size is larger than the aperture such that the barb isretained by the receiver and escapement of the barb through the apertureis prevented by interference between the barb and the end wall in thefirst configuration, wherein configuring the barb to the firstconfiguration can include actuating, by a linear actuator, at least onearm linked to the linear actuator, and retracting, based on theactuating, the arm from the first configuration in which the arm extendsfrom the shaft a first distance to define the first size, to the secondconfiguration in which the arm extends from the shaft a second distanceless than the first distance to define the second size. For example, theactuation rod 1422 can be moved linearly by a linear actuator to causethe arms 1444 a, 1444 b to extend and retract, expanding and shrinkingthe overall size of the barb 1440. In the expanded configuration, thebarb 1440 is too large to be retracted back through the aperture 482. Inthe retracted configuration, the barb 1440 is small enough to beescapable from the receiver assembly 450 through the aperture 482.

In some embodiments, the barb can be is spring-biased to the first size.For example, the barb 440 can be spring biased to the locked rotationalposition in which the rotational position of the barb 440 relative tothe aperture 482 makes the barb 440 too large to escape through theaperture 482. In another example, the arms 1044 a, 1044 b of the barb1040 can be spring biased to the larger, open configuration. In anotherexample, the actuation rod 1422 and/or the arms 1444 a, 1444 b can bespring biased to cause the arms 1444 a, 1444 b to open to the larger,open configuration.

Although a few implementations have been described in detail above,other modifications are possible. For example, the logic flows depictedin the figures do not require the particular order shown, or sequentialorder, to achieve desirable results. In addition, other steps may beprovided, or steps may be eliminated, from the described flows, andother components may be added to, or removed from, the describedsystems. Accordingly, other implementations are within the scope of thefollowing claims.

1-12. (canceled)
 13. A method of operating a thrust reverser tertiarylock, comprising: locking a thrust reverser tertiary lock by:penetrating, by a barb at a first end of a shaft of a probe, an aperturedefined in an end wall of a receiver shaped to accommodate the barb;configuring the barb to a first configuration; and preventing, by theend wall, escapement of the barb though the aperture in the firstconfiguration; and unlocking the thrust reverser tertiary lock by:configuring the barb to a second configuration; and permittingescapement of the barb through the aperture in the second configuration.14. The method of claim 13, wherein locking the thrust reverser tertiarylock further comprises: configuring, while in an escaped configuration,the barb to the first configuration; contacting the barb to an edge ofthe aperture, wherein contact between the barb and the edge urges thebarb from the first configuration to the second configuration;penetrating, by the probe, the aperture; and reconfiguring, after thebarb has passed through the aperture, the barb to the firstconfiguration.
 15. The method of claim 14, wherein the barb comprises abevel configured to contact the edge of the aperture and urge rotationof the barb about a primary axis of the shaft from the firstconfiguration to the second configuration during penetration of theaperture by the barb.
 16. The method of claim 14, wherein the edge ofthe aperture comprises a bevel configured to contact the barb and urgerotation of the barb about a primary axis of the shaft from the firstconfiguration to the second configuration during penetration of theaperture by the barb.
 17. The method of claim 14, reconfiguring, afterthe barb has passed through the aperture, the barb to the firstconfiguration, further comprises rotating, by a torsion bias spring, thebarb about the axis from the first configuration to the secondconfiguration after the barb has completed penetration of the bevel. 18.The method of claim 14, wherein the barb comprises an arm having a firstend that is pivotably connected to the shaft and configured to contactan edge of the aperture and pivot toward the shaft from the firstconfiguration to the second configuration to pass through the apertureduring penetration of the end wall by the barb, and configured to pivotaway from the shaft from the second configuration to the firstconfiguration and interfere with escapement of the barb in the firstconfiguration.
 19. The method of claim 13, wherein configuring the barbto the first configuration comprises rotating, by a rotary actuator, thebarb about an axis from a second rotary position to a first rotaryposition.
 20. The method of claim 13, wherein configuring the barb tothe second configuration comprises rotating, by a rotary actuator, thebarb about an axis from a first rotary position to a second rotaryposition.
 21. The method of claim 13, wherein the barb has a first sizein the first configuration and has a second size in the secondconfiguration, wherein the second size is smaller than the aperture suchthat the barb is able to penetrate and escape the aperture in the secondconfiguration, and the first size is larger than the aperture such thatthe barb is retained by the receiver and escapement of the barb throughthe aperture is prevented by interference between the barb and the endwall in the first configuration; and wherein configuring the barb to thefirst configuration comprises: actuating, by a linear actuator, at leastone arm linked to the linear actuator; extending, based on theactuating, the arm from the second configuration in which the armextends from the shaft a first distance to define the first size, to thefirst configuration in which the arm extends from the shaft a seconddistance greater than the first distance to define the second size. 22.The method of claim 13, wherein the barb has a first size in the firstconfiguration and has a second size in the second configuration, whereinthe second size is smaller than the aperture such that the barb is ableto penetrate and escape the aperture in the second configuration, andthe first size is larger than the aperture such that the barb isretained by the receiver and escapement of the barb through the apertureis prevented by interference between the barb and the end wall in thefirst configuration; and wherein configuring the barb to the firstconfiguration comprises: actuating, by a linear actuator, at least onearm linked to the linear actuator; and retracting, based on theactuating, the arm from the first configuration in which the arm extendsfrom the shaft a first distance to define the first size, to the secondconfiguration in which the arm extends from the shaft a second distanceless than the first distance to define the second size.
 23. The methodof claim 22, wherein the barb is spring-biased to the first size.